This application is based upon and claims benefit of priority of Japanese Patent Application No. 2002-243808 filed on Aug. 23, 2002, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a connector for electrically connecting a button battery to a circuit board contained in an electronic device, and further relates to an electronic device in which the connector is used.
2. Description of Related Art
An example of a conventional connector for electrically connecting a button battery to a circuit board contained in an electronic device is shown in FIGS. 8A and 8B. A connector 500 made of a conductive metallic plate is composed of a pair of resilient arms 51 and a stay 502 for supporting the resilient arms 51. The pair of resilient arms 51 contacts a plus terminal of a button battery, the plus terminal being circularly formed around an outer periphery of the button battery. The stay 502 is fixed to a surface of a circuit board 20 by soldering.
The stay 502 has to be made in such a size (including its length L3) that the connector 500 is firmly fixed to the circuit board by soldering, withstanding a force applied to the connector 500 by resiliently inserting the button battery into the pair of resilient arms 51. If the stay 502 is not sufficiently large, it may be peeled off from the circuit board and electrical connection of the button battery cannot be maintained. Further, if the stay size is small, the connector 500 cannot keep its horizontal posture on the circuit board when it is placed on the circuit board for soldering, because a weight balance between the resilient arms 51 and stay 502 becomes unequal, and thereby the connector 500 falls down toward the resilient arms 51. On the other hand, it is desirable to make the stay size as small as possible to save a soldering area on the circuit board.
The present invention has been made in view of the above-mentioned problem, and an object of the present invention is to provide an improved connector for connecting a button battery to a circuit board. More particularly, an object of the present invention is to provide a connector having a stay that is able to keep its weight balance and is able to save a soldering space on a circuit board.
An electronic device such as transmitter for wirelessly sending signals for operating a keyless entry system of an automobile contains a button battery therein. The button battery has a plus terminal circularly formed around its outer periphery and a minus terminal formed on one flat surface of the button battery. The button battery is electrically connected to a circuit board contained in the electronic device through a plus connector contacting the plus terminal and a minus connector contacting the minus terminal. Both connectors are mounted on a surface of the circuit board by soldering.
The plus connector includes a pair of resilient arms resiliently contacting the plus terminal of the button battery, a main stay connected to a rear side of the resilient arms (a side opposite to a side where the battery is positioned), and an auxiliary stay connected to a front side of the resilient arms (a side where the battery is positioned). The plus connector, as a whole, is integrally formed from a conductive metallic plate. Both stays support the plus connector on a surface of the circuit board, and at least the main stay is fixed to the surface by re-flow soldering. Alternatively, both stays may be fixed to the surface.
The plus connector is supported by both stays on the surface of the circuit board when the connector is placed on the surface for soldering. Therefore, the plus connector can keep its correct posture on the circuit board without enlarging the stay size only for keeping the posture of the connector. The stays can be made in such a size that is enough to secure a required bonding strength to the circuit board. Accordingly, a space for soldering the plus connector on the circuit board can be minimized. Preferably, the stays are formed in a rectangular or polygonal shape to avoid rotation of the plus connector relative to the circuit board in the re-flow soldering process.
The button battery may be held in a battery holder, made of an insulating resin material, supported on the circuit board. In this case, a terminal cover is integrally formed with the battery holder and is placed between the auxiliary stay and the minus terminal of the battery to secure insulation therebetween.
According to the present invention, the stays supporting the plus connector can be made small in size while ensuring that the plus connector keeps its correct posture in the process of soldering. Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiments described below with reference to the following drawings.